The meeting didn't reach any binding agreements, it simply established that the rulers of each level would not infringe on each other's territories, as well as continue to fulfill the duty of being part of the labyrinth—preventing adventurers from exploring deeper levels.
The Land of Nightmare sort of abided by the first rule, after all, the Little Demons didn't have much of a need for territory, and the environments on the other floors weren't comfortable for them either.
As for the second agreement, it was not taken seriously, not just by Qianqian, but most of the level rulers were insincere in their compliance.
After all, since the warlords in the deeper levels of the labyrinth had cut off supplies to the upper levels, there was really no reason for them to risk being killed by adventurers to protect the interests of those misers.
On the contrary, they actually hoped that the surface adventurers would invade deep into the labyrinth.